Phenotypic assessment of antiviral activity for spiro-annulated oxepanes and azepenes.

Evolutionary potential of viruses can result in outbreaks of well-known viruses and emergence of novel ones. Pharmacological methods of intervening the reproduction of various less popular, but not less important viruses are not available, as well as the spectrum of antiviral activity for most known compounds. In the framework of chemical biology paradigm, characterization of antiviral activity spectrum of new compounds allows to extend the antiviral chemical space and provides new important structure-activity relationships for data-driven drug discovery. Here we present a primary assessment of antiviral activity of spiro-annulated derivatives of seven-membered heterocycles, oxepane and azepane, in phenotypic assays against viruses with different genomes, virion structures, and genome realization schemes: orthoflavivirus (tick-borne encephalitis virus, TBEV), enteroviruses (poliovirus, enterovirus A71, echovirus 30), adenovirus (human adenovirus C5), hantavirus (Puumala virus). Hit compounds inhibited reproduction of adenovirus C5, the only DNA virus in the studied set, in the yield reduction assay, and did not inhibit reproduction of RNA viruses.

Pre-Clinical Studies of Inactivated Polyvalent HFRS Vaccine.

Hemorrhagic fever with renal syndrome (HFRS) is the most common natural focal disease in the Russian Federation with about 6-12 thousand cases annually. 97.7% of all HFRS cases in Russia are caused by the Puumala virus, 1.5%-by the Hantaan, Amur, Seoul viruses, and about 0.8% by the Kurkino and Sochi viruses. There are no licensed vaccines for the prevention of HFRS in the European Region; there are no specific therapeutic to treat orthohantavirus infections. Here we report the results of candidate polyvalent HFRS vaccine preclinical studies. The vaccine was produced on the basis of three viruses: Puumala, strain PUU-TKD/VERO, Hantaan, strain HTN-P88/VERO, and Sochi, strain DOB-SOCHI/VERO. These viruses were inactivated with ß-propiolacton, purified by gel filtration and aluminum hydroxide adsorbed. 18-20 g female BALB/c mice were immunized intramuscularly 2 or 3 times with a 2-week intervals and blood was taken 2 weeks after immunization. FRNT50 performed for virus specific antibodies determination. ELISA kits (Bender MedSystems, Cusabio) were used for detection of cytokines IL-1ß, IL-12, INF-É£. Neutralizing antibodies geometric mean titers to the Puumala, Hantaan, and Sochi viruses were: 9.22 ± 0.31, 9.17 ± 0.26, 8.96 ± 0.34 log2/ml. Up to 1/32 vaccine dilution neutralizing antibodies were identified in 10/10 immunized mice with titers ≥ 3,32 log2/ml. IL-12 and INF-É£ increased after immunization in average 5.5 and 2.8 times respectively, that reflects the Th1 type immunity stimulation. IL-1ß slightly increased, that may suggest vaccine low reactogenicity. According to our preclinical investigations, the candidate polyvalent HFRS vaccine elicits balanced immune response to the Puumala, Hantaan and Sochi viruses.

Various Adjuvants Effect on Immunogenicity of Puumala Virus Vaccine.

Various adjuvant effects on the immunogenicity of the candidate inactivated Puumala virus vaccine were detected in BALB/c mice. Adjuvants under study were: aluminum hydroxide, spherical particles of Tobacco mosaic virus coat protein, B subunit of heat-labile enterotoxin of Escherichia coli, and low endotoxic lipopolysaccharide of Shigella sonnei. Aluminum hydroxide (1 mg/ml) did not affect neutralizing antibodies' induction and vaccine stability during storage compared to immunization with the vaccine without adjuvant. B subunit of heat-labile enterotoxin (0.2 µg/ml), low endotoxic lipopolysaccharide (50 µg/ml), and plant virus-based spherical particles (300 µg/ml) significantly enhance the humoral immune response of vaccine (p < 0.0001). Pronounced stimulation of IL-12 and IFN-É£ was observed when mice were immunized with vaccines both with adjuvants (except of aluminum hydroxide) and without adjuvants. It has been shown that low endotoxic lipopolysaccharide contributes not only to enhance the immune response but also to stabilize vaccine immunogenicity during at least 1 year storage.

Hemorrhagic Fever with Renal Syndrome, Russia.

In Russia, 131,590 cases of hemorrhagic fever with renal syndrome caused by 6 different hantaviruses were reported during 2000-2017. Most cases, 98.4%, were reported in western Russia. The average case-fatality rate was 0.4%, and strong regional differences were seen, depending on the predominant virus type.